Cooperative Cloud-Edge Feature Extraction Architecture for Mobile Image Retrieval

Table 1

Frequently used symbols.

Symbols	Descriptions
	The pixel matrix of an image data set
	The i-th image in the image data set
	The mean of the image
	The j-th feature of the i-th image
	The standard deviation of the j-th feature
	The covariance matrix for the features in the image data set
	The projection matrix
	The Euclidean distance between two vectors
	The accuracy rate of the feature matching
	Step function, equals if and equals otherwise
	K-nearest neighbor